High performance seal assembly for a gas turbine engine

ABSTRACT

A foil comprising longitudinal edge portions separated by a central portion has one longitudinal edge portion attached to a shoe that slides against a regenerator. The central portion projects away from the shoe to contact the engine housing. The other longitudinal edge portion curves back toward the shoe and floats into and out of contact with the shoe during dimension variations caused by temperature or pressure changes.

United States Patent [191 Vallance HIGH PERFORMANCE SEAL ASSEMBLY FOR A GAS TURBINE ENGINE [75] Inventor: James K. Vallance, Dearborn Heights, Mich.

[73] Assigneeg l ord Motor Company; Dearborn,

'Mioh.

[22] Filed: Nov. 15, 1971 [21] Appl. No.: 198,678

[52] U.S. Cl 165/9, 277/81 R, 277/88 [51] Int. Cl. F28d 19/00 [58] Field of Search 165/9; 277/81 R, 88, 89, 277/90, 95, 175

[56] References Cited UNITED STATES PATENTS 3,559,725 2/1971 Fucinari et a1 165/9 3,622,737 11/1971 Trudeau I 165/9 3,234,999 2/1966 Atvvood 165/9 Apr. 23, 1974 3,273,904 9/1966 Chapman ct a1 165/9 X 3,534,808 10/1970 Carroll 165/9 FOREIGN PATENTS OR APPLICATIONS 763,385 \l2/l956 Great Britain 165/9 Primary Examiner-Albert W. Davis, Jr. Attorney, Agent, or Firm-Donald J. Harrington; Keith L. Zerschling [571 ABSTRACT A foil comprising longitudinal edge portions separated by a central portion has one longitudinal edge portion attached to a shoe that slides against a regenerator. The central portion projects away from theshoe to contact the engine housing. The: other longitudinal edge portion curves back toward the shoe and floats into and out of contact with the shoe during dimension variations caused by temperature or pressure changes. i

8 Claims, 4 Drawing Figures HIGH PERFORMANCE SEAL ASSEMBLY FOR A GAS TURBINE ENGINE SUMMARY OF THE INVENTION This invention is related to the subject matter of US. Pat. No. 3,741,288, granted June 26, 1973 and entitled PREFORMED SEAL ASSEMBLY FOR A GAS TUR- BINE REGENERATOR, and US. Pat. No. 3,719,226, granted Mar. 6, 1973 and entitled SEAL ASSEMBLY FOR A GAS TURBINE REGENERATOR.

The regenerators of current regenerative type gas turbine engines typically operate at temperatures ranging up to about 1,300F and pressures ranging up to about 4 atmospheres. Efficiency can be improved considerably by raising operating temperatures and pressures, but higher temperatures increase the relative thermal growth between the metal engine housing and the ceramic regenerator and thus seriously complicate sealing problems. Higher pressures not only increase the loads applied to the regenerator seal but also magnify the thermally induced dimensional variations by causing more severe deflection'of engine components.

This invention provides a high performance seal as sembly for a gas turbine engine that is capable of absorbing greater dimensional changes under greater pressure differentials. In a gas turbine engine having a regenerator rotating in a housing with sectors of the re-' generator being subjected to gas streams of different pressures, the seal assembly comprises a shoe having one surface rubbing against the regenerator. A foil has one located longitudinal edge portion attached to the shoe. The central longitudinal portion of the foil projects away from the shoe and contacts the engine housing. The other longitudinal edge portion curves back toward the shoe and terminates in a floating position between the shoe and the housing. Dimensional variations in the distance between the shoe and the adjacent portion of the housing move the floating longitudinal edge portion into and out of contact with the shoe.

best with a plurality of short contacting portions spaced along the length of the floating longitudinal edge portion. Straight cross arm seal assemblies can have a continuous contact portionextendingsubstantially the entire length of the floating edge portion. Each end of the contact portions preferably is defined by a cutout section extending for a short distance into the foil beyond the contact portion. The cutouts insure pneumatic communication between the gas pressure exterior of thefoil and the space between the foil and the shoe.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view through the regenerator portion of a gas turbine engine showing the relationship of seal assemblies of this invention to an engine housing and a disc-shaped regenerator mounted therein. FIG. 2

Seal assemblies of this invention serve effectively as is a plan view of a peripheral seal assembly of this invention that shows a continuous contact portion extending along virtually the entire length of the floating edge of the foil. A plurality of cutouts are spaced equally along the contact portion. FIG. 3 is a sectionalview of a seal assembly of this invention showing the relationship between the located longitudinal edge portion, the central longitudinal portion and the floating longitudinal edge portion. FIG. 4 is a plan view of an alternate peripheral seal assembly that has a plurality of short contacting portions spaced along the floating longitudinal edge of the foil.

DETAILED DESCRIPTION Referring primarily to FIG; 1, a gas turbine engine containing the sealing system of this invention has an elliptically-shaped metal outer housing 10 that is open at the top of the regenerator portion (FIG. 1 is seetioned along the major diameter of the ellipse). A circular inner wall 12 merges with the housing 10 at one side to define a circular passage that is divided diamet rically by a wall 16 into two semi-circular passages 18 and 20. Wall 12 and the left portion of outer housing 10 define an annularpassage 22. The sides of the walls defining passages 18 and 20 are covered with appropriate insulation 23. i

A disc-shaped regenerator 24 is mounted rotatably above wall 12. An annular ring gear 26 surrounds the regenerator 24 and meshes with .a pinion gear 28 that is supported on the inner surface of housing 10 by projecting bosses 30 and 32. Pinion gear 28 is driven by the gas turbine engine through ashaft 34located in annular passage 22 and the pinion gear in turn drives regenerator 24 through ring gear 26 and an appropriate torque transmitting member 35. A metalcover 36 is attached to outer housing 10 by conventional means (not shown) and covers the open portion of the outer housing. Cover 36 has a downwardly projecting ridge 38 that is aligned with diametrical wall 16.

An inner sealing system seals appropriate junctions between the inner surface of regenerator 24 and walls 12 and 16. The inner sealing system comprises two C- shaped peripheral seal assemblies 40 and 42 and an inner crossarm seal assembly 44. Each of seal assemblies 40, .42 and 44 includes a respective shoe, 46, 48 and 50 having one surface sliding against the regenerator. Opposite surfaces of each shoe have one edge of a respective foil52, 54 and 56 attached thereto. The outer-edge of each foil projects'toward. an appropriate surface of walls 12 and 16. I

A D-shaped outer seal assembly 60 seals appropriate junctions between theouter surfac e'of regenerator 24. and cover 36. Outer seal assembly 60cornprises a shoe 62 having a peripheral portion extending around the right sector of regenerator 24 and a crossarm portion extending across" the regenerator below ridge 38. One surface of shoe 62 slides against the outer surface of re generator 24. One edge of a projecting foil 66 is attached to the inner portion of the outersurface of the peripheral portion and its projecting edge extends upward and outward to contact cover 36. One edge of a projecting foil 68 is attached to the right side of the outer surface of the crossarm portion of shoe 62 and its other edge projects upward, and outward to contact ridge 38. The projecting foils typically are made of stainless steel or-high temperature nickel alloys.

FIGS. 2 and 3 illustrate further details of seal assembly 42. The inner longitudinal edge portion 70 of foil 54 is positioned on shoe 48 by welding. Central longitudinal portion 72 projects outwardly away from positioned portion 70 and contacts the engine housing as illustrated in FIG. 1. The outer longitudinal edge portion 74 curves back toward shoe 48 to terminate in a floating position between the shoe and the housing. Portion 74 includes a relatively narrow contact portion 76 that extends along the entire length of foil 54 except for the ends thereof as illustrated in FIG. 2. Central portion 72 curves into contact portion 74 so the contact portion is substantially parallel to shoe 48 when the contact portion contacts the shoe. A plurality of spaced cutouts 78 are formed in contact portion 76. The cutouts extendslightly beyond the contact portion to insure that adequate gas pressure is maintained between the foil and the shoe. Similar foil constructions are used in seal assemblies 40, 44 and 60.

During engine operation, temperature and pressure differentials decrease the spaces occupied by some of the seal assemblies and increase the spaces occupied by other seal assemblies. In a decreasing space, the housing bears on the foil of the seal to move the contact portion 76 of the foil into contact with the appropriate shoe. After the contact portion reaches the shoe, further decreases in the space deflect the central portion of the foil without permanent deformation. In an expanding space, foil preload and air pressure combine to maintain the central portion 72 of the foil in sealing contact with an appropriate portion of the engine housing. v Turning to the alternate foil construction shown in FIG. 4, a positioned longitudinal edge portion 700 is attached to an appropriate shoe as described'above. Central portion 72a extends outwardly away from positioned edge portion 70a and the outer longitudinal edge portion curves back toward the shoe surface. Edge portion 74a contains three relatively short contact portions 76a that are spaced along the length of the edge portion. A cutout 78a defines each end of each contact portion 76a. Seal performance occurs in the manner described above.

Thus this invention provides a high performance seal assembly for sealing junctions between the regenerator and the housing of a gas turbine engine. The sea] assembly maintains sealing contact over a wide range of temperatures and pressures and absorbs large variations in the dimensions of the junctions without permanently folding or creasing. 1

I claim:

1. In a gas turbine engine having a regenerator rotating in a housing with sectors of said regenerator being subjected to gas streams of different'pressures, a seal assembly for sealing between said gas streams comprisa shoe having one surface for rubbing against the regenerator,

a foil having onelocated longitudinal edge portion attached to the shoe, a central longitudinal portion, and a floating longitudinal edge portion, said central portion projecting away from said shoe and contacting an adjacent portion of said housing, said floating longitudinal edge portion curving away from said adjacent portion of said housing and toward said shoe, said floating longitudinal edge portion being adapted to move into and out of contact with said shoe during changes in the distance between the shoe and the adjacent portion of the housing and passages formed in said foil at radial locations between said floating longitudinal edge portion and the region of contact between said central longitudinal portion and said adjacent housing portion whereby pressure from high pressure regions of said engine establish sealing forces on said foil.

2. The engine of claim 1 in which the floating longitudinal edge portion comprises a contact portion substantially parallel to a surface of said shoe when the floating longitudinal edge portion contacts the shoe.

3. The engine of claim 2 in which the contact portion is located at the longitudinal edge of said floating longitudinal edge portion. I

4. The engine of claim 3 in which the longitudinal edge of said floating longitudinal edge portion comprises a plurality of cutouts spaced along its length, said cutouts extending beyond the contact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe.

5. The engine of claim 4 comprising a plurality of short contact portions spaced along the length of the floating longitudinal edge portion, and a cutout at each end of each contact portion.

6. The engine of claim 2 in which the longitudinal edge of said floating longitudinal edge portion comprises a plurality of cutouts spaced along its length, said cutouts extending beyond the contact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe.

7. The engine of claim 1 inwhich the floating longitudinal edge portion comprises a plurality of short contact portions spaced longitudinally along the edge, portion, said contact portions being substantially parallel to a surface of said shoe when the floating'longitudinal edge portion contacts the shoe.

8. The engine of claim 7 comprising a cutout at each end of each contact portion, said cutouts extending beyond the contact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe. 

1. In a gas turbine engine having a regenerator rotating in a housing with sectors of said regenerator being subjected to gas streams of different pressures, a seal assembly for sealing between said gas streams comprising a shoe having one surface for rubbing against the regenerator, a foil having one located longitudinal edge portion attached to the shoe, a central longitudinal portion, and a floating longitudinal edge portion, said central portion projecting away from said shoe and contacting an adjacent portion of said housing, said floating longitudinal edge portion curving away from said adjacent portion of said housing and toward said shoe, said floating longitudinal edge portion being adapted to move into and out of contact with said shoe during changes in the distance between the shoe and the adjacent portion of the housing and passages formed in said foil at radial locations between said floating longitudinal edge portion and the region of contact between said central longitudinal portion and said adjacent housing portion whereby pressure from high pressure regions of said engine establish sealing forces on said foil.
 2. The engine of claim 1 in which the floating longitudinal edge portion comprises a contact portion substantially parallel to a surface of said shoe when the floating longitudinal edge portion contacts the shoe.
 3. The engine of claim 2 in which the contact portion is located at the longitudinal edge of said floating longitudinal edge portion.
 4. The engine of claim 3 in which the longitudinal edge of said floating longitudinal edge portion comprises a plurality of cutouts spaced along its length, said cutouts extending beyond the cOntact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe.
 5. The engine of claim 4 comprising a plurality of short contact portions spaced along the length of the floating longitudinal edge portion, and a cutout at each end of each contact portion.
 6. The engine of claim 2 in which the longitudinal edge of said floating longitudinal edge portion comprises a plurality of cutouts spaced along its length, said cutouts extending beyond the contact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe.
 7. The engine of claim 1 in which the floating longitudinal edge portion comprises a plurality of short contact portions spaced longitudinally along the edge portion, said contact portions being substantially parallel to a surface of said shoe when the floating longitudinal edge portion contacts the shoe.
 8. The engine of claim 7 comprising a cutout at each end of each contact portion, said cutouts extending beyond the contact portion to provide pneumatic communication from the foil exterior to the space between the foil and the shoe. 